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 /*

  * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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  */

 #include "precompiled.hpp"

 #include "code/codeCache.hpp"

 #include "code/nmethod.hpp"

 #include "gc_implementation/g1/g1CodeCacheRemSet.hpp"

 #include "gc_implementation/g1/heapRegion.hpp"

 #include "memory/heap.hpp"

 #include "memory/iterator.hpp"

 #include "oops/oop.inline.hpp"

 #include "utilities/hashtable.inline.hpp"

 #include "utilities/stack.inline.hpp"

 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

 class CodeRootSetTable : public Hashtable<nmethod*, mtGC> {

   friend class G1CodeRootSetTest;

   typedef HashtableEntry<nmethod*, mtGC> Entry;

   static CodeRootSetTable* volatile _purge_list;

   CodeRootSetTable* _purge_next;

   unsigned int compute_hash(nmethod* nm) {

     uintptr_t hash = (uintptr_t)nm;

     return hash ^ (hash >> 7); // code heap blocks are 128byte aligned

   }

   void remove_entry(Entry* e, Entry* previous);

   Entry* new_entry(nmethod* nm);

  public:

   CodeRootSetTable(int size) : Hashtable<nmethod*, mtGC>(size, sizeof(Entry)), _purge_next(NULL) {}

   ~CodeRootSetTable();

   // Needs to be protected locks

   bool add(nmethod* nm);

   bool remove(nmethod* nm);

   // Can be called without locking

   bool contains(nmethod* nm);

   int entry_size() const { return BasicHashtable<mtGC>::entry_size(); }

   void copy_to(CodeRootSetTable* new_table);

   void nmethods_do(CodeBlobClosure* blk);

   template<typename CB>

   int remove_if(CB& should_remove);

   static void purge_list_append(CodeRootSetTable* tbl);

   static void purge();

   static size_t static_mem_size() {

     return sizeof(_purge_list);

   }

   size_t mem_size();

 };

 CodeRootSetTable* volatile CodeRootSetTable::_purge_list = NULL;

 size_t CodeRootSetTable::mem_size() {

   return sizeof(CodeRootSetTable) + (entry_size() * number_of_entries()) + (sizeof(HashtableBucket<mtGC>) * table_size());

 }

 CodeRootSetTable::Entry* CodeRootSetTable::new_entry(nmethod* nm) {

   unsigned int hash = compute_hash(nm);

   Entry* entry = (Entry*) new_entry_free_list();

   if (entry == NULL) {

     entry = (Entry*) NEW_C_HEAP_ARRAY2(char, entry_size(), mtGC, CURRENT_PC);

   }

   entry->set_next(NULL);

   entry->set_hash(hash);

   entry->set_literal(nm);

   return entry;

 }

 void CodeRootSetTable::remove_entry(Entry* e, Entry* previous) {

   int index = hash_to_index(e->hash());

   assert((e == bucket(index)) == (previous == NULL), "if e is the first entry then previous should be null");

   if (previous == NULL) {

     set_entry(index, e->next());

   } else {

     previous->set_next(e->next());

   }

   free_entry(e);

 }

 CodeRootSetTable::~CodeRootSetTable() {

   for (int index = 0; index < table_size(); ++index) {

     for (Entry* e = bucket(index); e != NULL; ) {

       Entry* to_remove = e;

       // read next before freeing.

       e = e->next();

       unlink_entry(to_remove);

       FREE_C_HEAP_ARRAY(char, to_remove, mtGC);

     }

   }

   assert(number_of_entries() == 0, "should have removed all entries");

   free_buckets();

   for (BasicHashtableEntry<mtGC>* e = new_entry_free_list(); e != NULL; e = new_entry_free_list()) {

     FREE_C_HEAP_ARRAY(char, e, mtGC);

   }

 }

 bool CodeRootSetTable::add(nmethod* nm) {

   if (!contains(nm)) {

     Entry* e = new_entry(nm);

     int index = hash_to_index(e->hash());

     add_entry(index, e);

     return true;

   }

   return false;

 }

 bool CodeRootSetTable::contains(nmethod* nm) {

   int index = hash_to_index(compute_hash(nm));

   for (Entry* e = bucket(index); e != NULL; e = e->next()) {

     if (e->literal() == nm) {

       return true;

     }

   }

   return false;

 }

 bool CodeRootSetTable::remove(nmethod* nm) {

   int index = hash_to_index(compute_hash(nm));

   Entry* previous = NULL;

   for (Entry* e = bucket(index); e != NULL; previous = e, e = e->next()) {

     if (e->literal() == nm) {

       remove_entry(e, previous);

       return true;

     }

   }

   return false;

 }

 void CodeRootSetTable::copy_to(CodeRootSetTable* new_table) {

   for (int index = 0; index < table_size(); ++index) {

     for (Entry* e = bucket(index); e != NULL; e = e->next()) {

       new_table->add(e->literal());

     }

   }

   new_table->copy_freelist(this);

 }

 void CodeRootSetTable::nmethods_do(CodeBlobClosure* blk) {

   for (int index = 0; index < table_size(); ++index) {

     for (Entry* e = bucket(index); e != NULL; e = e->next()) {

       blk->do_code_blob(e->literal());

     }

   }

 }

 template<typename CB>

 int CodeRootSetTable::remove_if(CB& should_remove) {

   int num_removed = 0;

   for (int index = 0; index < table_size(); ++index) {

     Entry* previous = NULL;

     Entry* e = bucket(index);

     while (e != NULL) {

       Entry* next = e->next();

       if (should_remove(e->literal())) {

         remove_entry(e, previous);

         ++num_removed;

       } else {

         previous = e;

       }

       e = next;

     }

   }

   return num_removed;

 }

 G1CodeRootSet::~G1CodeRootSet() {

   delete _table;

 }

 CodeRootSetTable* G1CodeRootSet::load_acquire_table() {

   return (CodeRootSetTable*) OrderAccess::load_ptr_acquire(&_table);

 }

 void G1CodeRootSet::allocate_small_table() {

   _table = new CodeRootSetTable(SmallSize);

 }

 void CodeRootSetTable::purge_list_append(CodeRootSetTable* table) {

   for (;;) {

     table->_purge_next = _purge_list;

     CodeRootSetTable* old = (CodeRootSetTable*) Atomic::cmpxchg_ptr(table, &_purge_list, table->_purge_next);

     if (old == table->_purge_next) {

       break;

     }

   }

 }

 void CodeRootSetTable::purge() {

   CodeRootSetTable* table = _purge_list;

   _purge_list = NULL;

   while (table != NULL) {

     CodeRootSetTable* to_purge = table;

     table = table->_purge_next;

     delete to_purge;

   }

 }

 void G1CodeRootSet::move_to_large() {

   CodeRootSetTable* temp = new CodeRootSetTable(LargeSize);

   _table->copy_to(temp);

   CodeRootSetTable::purge_list_append(_table);

   OrderAccess::release_store_ptr(&_table, temp);

 }

 void G1CodeRootSet::purge() {

   CodeRootSetTable::purge();

 }

 size_t G1CodeRootSet::static_mem_size() {

   return CodeRootSetTable::static_mem_size();

 }

 void G1CodeRootSet::add(nmethod* method) {

   bool added = false;

   if (is_empty()) {

     allocate_small_table();

   }

   added = _table->add(method);

   if (added) {

     if (_length == Threshold) {

       move_to_large();

     }

     ++_length;

   }

   assert(_length == (size_t)_table->number_of_entries(), "sizes should match");

 }

 bool G1CodeRootSet::remove(nmethod* method) {

   bool removed = false;

   if (_table != NULL) {

     removed = _table->remove(method);

   }

   if (removed) {

     _length--;

     if (_length == 0) {

       clear();

     }

   }

   assert((_length == 0 && _table == NULL) ||

          (_length == (size_t)_table->number_of_entries()), "sizes should match");

   return removed;

 }

 bool G1CodeRootSet::contains(nmethod* method) {

   CodeRootSetTable* table = load_acquire_table(); // contains() may be called outside of lock, so ensure mem sync.

   if (table != NULL) {

     return table->contains(method);

   }

   return false;

 }

 void G1CodeRootSet::clear() {

   delete _table;

   _table = NULL;

   _length = 0;

 }

 size_t G1CodeRootSet::mem_size() {

   return sizeof(*this) + (_table != NULL ? _table->mem_size() : 0);

 }

 void G1CodeRootSet::nmethods_do(CodeBlobClosure* blk) const {

   if (_table != NULL) {

     _table->nmethods_do(blk);

   }

 }

 class CleanCallback : public StackObj {

   class PointsIntoHRDetectionClosure : public OopClosure {

     HeapRegion* _hr;

    public:

     bool _points_into;

     PointsIntoHRDetectionClosure(HeapRegion* hr) : _hr(hr), _points_into(false) {}

     void do_oop(narrowOop* o) {

       do_oop_work(o);

     }

     void do_oop(oop* o) {

       do_oop_work(o);

     }

     template <typename T>

     void do_oop_work(T* p) {

       if (_hr->is_in(oopDesc::load_decode_heap_oop(p))) {

         _points_into = true;

       }

     }

   };

   PointsIntoHRDetectionClosure _detector;

   CodeBlobToOopClosure _blobs;

  public:

   CleanCallback(HeapRegion* hr) : _detector(hr), _blobs(&_detector, !CodeBlobToOopClosure::FixRelocations) {}

   bool operator() (nmethod* nm) {

     _detector._points_into = false;

     _blobs.do_code_blob(nm);

     return !_detector._points_into;

   }

 };

 void G1CodeRootSet::clean(HeapRegion* owner) {

   CleanCallback should_clean(owner);

   if (_table != NULL) {

     int removed = _table->remove_if(should_clean);

     assert((size_t)removed <= _length, "impossible");

     _length -= removed;

   }

   if (_length == 0) {

     clear();

   }

 }

 #ifndef PRODUCT

 class G1CodeRootSetTest {

  public:

   static void test() {

     {

       G1CodeRootSet set1;

       assert(set1.is_empty(), "Code root set must be initially empty but is not.");

       assert(G1CodeRootSet::static_mem_size() == sizeof(void*),

           err_msg("The code root set's static memory usage is incorrect, " SIZE_FORMAT " bytes", G1CodeRootSet::static_mem_size()));

       set1.add((nmethod*)1);

       assert(set1.length() == 1, err_msg("Added exactly one element, but set contains "

           SIZE_FORMAT " elements", set1.length()));

       const size_t num_to_add = (size_t)G1CodeRootSet::Threshold + 1;

       for (size_t i = 1; i <= num_to_add; i++) {

         set1.add((nmethod*)1);

       }

       assert(set1.length() == 1,

           err_msg("Duplicate detection should not have increased the set size but "

               "is " SIZE_FORMAT, set1.length()));

       for (size_t i = 2; i <= num_to_add; i++) {

         set1.add((nmethod*)(uintptr_t)(i));

       }

       assert(set1.length() == num_to_add,

           err_msg("After adding in total " SIZE_FORMAT " distinct code roots, they "

               "need to be in the set, but there are only " SIZE_FORMAT,

               num_to_add, set1.length()));

       assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");

       size_t num_popped = 0;

       for (size_t i = 1; i <= num_to_add; i++) {

         bool removed = set1.remove((nmethod*)i);

         if (removed) {

           num_popped += 1;

         } else {

           break;

         }

       }

       assert(num_popped == num_to_add,

           err_msg("Managed to pop " SIZE_FORMAT " code roots, but only " SIZE_FORMAT " "

               "were added", num_popped, num_to_add));

       assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");

       G1CodeRootSet::purge();

       assert(CodeRootSetTable::_purge_list == NULL, "should have purged old small tables");

     }

   }

 };

 void TestCodeCacheRemSet_test() {

   G1CodeRootSetTest::test();

 }

 #endif